Apparatus for making pistons



Dec. 7, 1937. G. H. BLETTNER APPARATUS- FOR MAKING PISTONS Filed'uarch 2, 1955 s sheets-sheet 1 mmv Patented Dec. 7, 1937 UNiTED STATES 2,101,043 APPARATUS FoR'MAKING Pls'roNs George-H. Blettner, Chicago, lll., assignor to Renette Company, Chicago, Ill., a corporation of Illinois Application March 2, 193s, serial No. 8,981

' 5 claims. (ol. :z2- 149) The present invention relates to an' apparatus for making pistons and more particularlytoa one piece piston, and so constructed and made as to enable its manufacture in quantity lots on 5 a production basis whereby the pistons may be sold at relatively low prices.

An object ofthe present invention is to provide an apparatus for molding a piston in horizontal position, which apparatus may be quick`y l and readily operated and in which a one piece core is employed in the mold cavity, which core is adapted to be withdrawn from the casting by horizontal movement.

Another object of the present invention is to l provide a one piece core for use in the manufacture of internal combustion engine and other pistons which core has self-contained extensible and retractible members or studs orradial projections or extensions to form the spaces between the wrist pin bosses and piston head.

A further object of the present invention has,

to do with a novel apparatus for casting internal combustion engine pistons in multiples or in groups of two or more at a time, in which the faxes of the piston cavities are horizontal and the skirt portions extend away from each other, the

apparatus being so constructed that metal `isv supplied to the larger voids of the piston cavities during cooling to compensate for crystallization` shrinkage.-

Another and yetfurther object of the present invention'is to provide an apparatus especially adapted to be rapidly operated for the manufacture of .pistons on a production basis and so con- Generally speaking the invention contemplates a permanent mold structure of two complementary sections or parts which are moved against or away from each other, in each`of which sections is formed a plurality of, complemental cavities for forming two pistons inhorizon-tal" positions with their heads in adjacentrelationship and the cavities opening toward 'the.ends of the mold structure. Each section also is provided with recesses'forming part of'an -ingate, risers, sprue, and an enlargement or expansion ball in` the ingate disposed between 55 the adjacent ends of the cavities for forming the,

section and the coresin elevation and, showing, in section, the cast pistons, the ingate, expansion heads of the pistons to supply metall to the 'heavier sections of the pistons during crystallization shrinkage. f.'

The invention further Vcontemplates a one piece core which is shaped to form the inside contoiurl 5 of the piston and which core is provided with two diametrically oppositelydisposed movable studs.

The invention contemplates the formation o f a multiple number of pistons ata time, thereby 10 expediting production and reducing labor costs.

The above other and further objects of the present invention will be apparent from the following description, accompanying drawings, and appended claims. i l5 -The accompanying drawings illustrate one embodiment of an apparatus constructedy in accordance with the principles of the present inf1 vention, arranged to cast two pistons at a tim and the views thereof are as follows: 1 20 Figure 1 is a side elevational view of one of the mold sections in casting position, withl the `cores in place, illustrating one manner of supporting the cores, and indicating, fragmentarlly, means for moving the cores axially into and out 25 of casting position. l

Figure 2 is an axial section through a piston constructed in accordance with the principles of the present invention, and showing the piston aiter is has been machined and in completed 30 form.

Figure 3 is a transverse sectional view taken substantially in the plane indicated by line III-III of Fig. 2.

Figure 4 is an elevational viewof the novel core y35 Y of the present invention.

Figure 5-is an axial section throughthe core of Figure 4.

Figure 6 is an end view of the core of Figure 1 4, looking at the right hand end of the same'.v 40

Figure 7 isan elevational view of the extensible and retractible members or studs carried by the core for forming the recesses or spaces in the piston between the wrist pin bosses and the piston head, showing the members in full lines `in retracted or nested position,. and in. dotted lines in extended or casting position.

Figure 8 is an axial sectional view, with a mold ball, risers and the sprue, and illustrating the method of the present invention. Figure 9 is atransverse vertical sectional vie through the mold and a cast piston, and showing core prints in place for forming the Wrist pin holes in the bosses. This view is a sectional View with the core removed, for clearness.

y Figure 10 is a rear elevational view of one of the extensible and retractible members or studs of the core. y The drawings will now be explained.

The illustrated form of permanent mold con-A sists of two sections A and B which are adapted to be moved against or away from each other. The sections are shown as hingedly connected by means of legs I and `2 on the sections A and B respectively which legs in turn are secured by bolts 3 and 4 to iianges 5 and 6 of a hinge which comprises eyes 1 and 8 and receiving a pintle pin 9.

The particular manner of mounting the mold on a standard support has not been illustrated as this may be accomplished in any well known and desirable manner.'

Each of the mold sections `is provided with complementary recesses which, when the sections are together, form-the mold cavities, the

y ingate and the risers.

e 'I'he section A is provided with two horizontally disposed cylindrical cavities I0, whichare axially spaced; two riser cavities II, of relatively shallow depth; an ingate I2 fashioned with an enlargement or expansion ball I3 disposed between the piston cavities I and connected thereto by passages I4 which communicates with the cavities substantially in horizontal direction, including the cavity axes, when the mold is in casting position; the lower end of theingate I2 communicates with axially/extending cavity or sprue vI5 which also supplies molten metal to the piston cavities from the bottoms of the same. The sprue cavity I5 is shallow as may be observed in- Flg. 9. 1

Each mold section is, at itsends, provided with a semicylindrical seat I6 for receiving and encompassing the cores which areinserted endwise into the mold cavitiesv by axial movement and removed therefrom by axial movement in the reverse direction.

Each of the mold sections is provided with'an upstanding head or neck I1 to form a bullet mold entrance for the ingate, and which extends above the mold sections to provide a head ofmolten y metal to compensate for crystallization shrinkage as the castings cool. l

As the two cores are alike in every respect, the description of one will suiice for both.

4 A core is fashioned from a block of steel and' comprises an end flange I8, a section I9 of reduced diameter, next to which is anothersection 20 of slightly less diameter, with the balance 2I,

in the main, cylindrical. 'Ihe flange I8 on the several sections are substantially cylindrical in thereof opening toward the other end of thev core body withtheir sides slightly divergent outwardly from the semi-circular ends.' A wall 23 is fashioned in each of the depressions lying inwardly of the surface `of the section 2I adjacent the depressions and .slightly inclined inwardly toward the inner end of the core, that is, the end opposite that on which the ange I8 is, which walls 23 serve a's abutments for the eds of core prints inserted in the mold sections A and B for fashioning the holes in the wrist pin bosses of the piston.

Secured in the core are two members or studs 24 and 25 which are adapted to be movable radially inwardly and outwardly, with respect to the cor'e axis for forming the spaces between the wrist pin bosses and the head of the piston when cast. The active ends of these members or studs 24 and 25 are shaped to form the recesses 26 in the pistons, see Figs. 2 and 3.

Figure is an inner elevational view of one of these members or studs which are constructed `as counterparts, and reversed in endwise arrangement when assembled in the core. Each of these studs is provided with an extension 21 irrI is cylindrical and carries two pins 32.and 33. The

pin 32 extends through the disc and has an end 32a projecting from theopposite face of the disc.

- 4The core body is provided with an arcuate recess 34 in which the projection 32a travels and which recess serves to limit the extent of rotative movement of the 'rod 3I in the core body. s The pins 32 and 33 enter the respective slots 28 in the two members 24 and-25, when assembled in: the core body as shown in Figs. 5 and 7. The members or studs 24 and 25 are retracted by voscillating the rod 3l in one direction, which would be clockwise as viewed in Fig. '7 and extended by oscillating the-rod in the opposite direction to substantially the dotted line position of Figs. 5 and '1. The extent of separation of the members or studs 24 and 25 is governed by the engagement of the extension 32a of the pin 32 in the arcuate recess 34 while the extent or movement in the opposite direction is limited by the two members coming together in retracted position, which is full line position of Figs. 5'and '1.

The members or studs 24 and 25 are retained against displacement with respect to the core by m'eans of a cover plate 68' retained in` position by means of screws 31 (Fig. 6).

In order to provide axially extending reinforcing ribs 38 on the interior of the skirt portion of the piston, the core is provided with axially extending grooves39 which increase in depth toward the inner end of the core.

` The outerend of the core is provided with a' counterbore 40 which is threaded at 4I for a pori tion of its length to receive the. threaded end of an operating rod 42, the receive the rod 3|.

A part of the apparatus includes vtwo uprights 43I and 44 disposed in spaced relation to the ends of themold and which uprights are provided with bearings 44 and 45 with which cooperate complemental bearing members 48 to receive the rods 42 of the two cores of the present apparatus. In order to move the cor'es into and out of rod is centrally bored to casting relationship, axially, with the molding' cavities in the mold sections, the rods 42 are provided' outwardly of the uprights 43 and 44 with blocks 41, each of which blocks carries trunnions 48 to which are pivotally connected swinging arms 49 adapted to move the rods 42.

The construction of the arms 49 is not fully shown but it is understood that these are pivends of the rods 42.

Aotally arranged and actuated by any well known means. a

To oscillate the rods 3I and the attached discs 3Ia, the extremities of the rods 3I are provided with handles 50 disposed outwardly of the uprights 43 and 44 and beyond the corresponding Each of the mold sections'A .and Bis provided. with a side opening 5I for receiving a core print 52 for the formation, in the nished piston, of

` the holes 53 for the wrist pin.

The meeting faces of the mold sections A and B are machined so as to aiford a tight iit between these parts when the same are connected together in casting relation to prevent the escape of any molten metal through the joints between them.

The operation of the apparatus is as follows:

When it is desired to castpistons utilizing the apparatus of the present invention, with the mold sections A and'B together, the cores C- and D are moved toward each other horizontally, .by operation of the levers 49, This movement positionsthe cores C-and D in proper relationship, within the mold cavities when the mold sections A and B are closed and so that the ends of the mold sections tightlyt about the sections I9 of the cores and the cores are then properly positioned within the mold cavities. The handles 50 are then actuated to oscillate the rods 3I in a direction to project or extendthe members or studs 2d and 25, to dotted line position of Figs; 5 and 7. The core pins 52 having been previously inserted in the mold sections A and B, or if not previously inserted, may now be inserted and moved lagainst the walls 24! of the cores.- The parts are now in position for pouring the molten of the head I'I, this, therefore, assures a sufli- .v cient head of molten metal in the ingate and the expansion ball to supply additional metal during coolingof the castings to compensate for the usual shrinkage. largement or expansion ball I3 adjacent the heads of the pistons assures at all times a supply of metal to the head portions of the pistons, and

- other heavier sections, so as to assure that the` heads are properly formed, and,'due to the supply of metal during cooling, formationof-cracks is prevented. The ,exterior o f the pistons is fashioned by the mold cavities in the mold sections A and B, while the cores C and D form' the interiors of these pstonsf The extensions of the members or studs 24 vand 25 `provide'spaces or recesses between the Wrist pin bosses. and the piston heads. The formationof the cores C and` D is such, that axially extending reinforcing ribs- 54 are cast in the pistons and also the wrist pin bosses 55. The ends of the skirt portions of the pistons are formed by the junction orv shoulder between the` portions I9 and 20 of the cores.

.When the casting operation has been completed, the handles 50 are operated in counter direction to withdraw or -retract 'the members or studs 24 or 25 within the cores C and D,- and the rods 42 are then moved outwardly by actuation of the leversk49, to withdraw thecores from the pistons, then the mold sections Aand B are\ The provision of the enseparated. when the mold sections A and B have been separated,'the finished product consisting ofthe two pistons and such portions of metal as may lie within the portion I5 of the gate, and the riser spaces I I, as well as in the ingate I2, enlargement I3, and branches I4 is then removed from the mold,- and when sumciently cooled, the pistons are separated from the scrap by sawing.

The piston blanks formed by the apparatus of the present invention are then subjected to suitable machine operations to form the piston ring grooves 56. three of which are shown and also to machine the inner periphery vof the skirt as at 51. The holes 53 in the wrist pin bosses may be machined, if necessary. The piston is then processed 4to provide slots 58 affording communication between the lowermost pistonring groove and the` interior of the piston for oil interchange in use. The outer portions of the piston are then ground to size and finish and the skirt issawed to provide a split 59, which extends i portion.

With an apparatus of the present invention as herein illustrated, it is possible to cast two pistons parts of the axially extending ribs 62 connecting the ribs 6l with the wrist pin bosses 55.

The nose of a core is fashioned by an'endpl'ate 60, shaped in elevation, as shown in Fig. i and retained in place by screw 31.

A piston made in accordance with the present invention is suitably reinforced and smoothly fin-- ished and in dimensions is substantially that of the nished piston.-

/ from one of the slots 58 to the margin of the skirt,

The present invention lends itself to rapid pro- A duction of uniform pistons so that the labor incidental to the molding operation is reduced to a minimum. The utilization of the permanent cores of the present invention is such that` no time is lost in setting the cores for the casting operations, so that the casting operations may be expedited for quantityproduction.

The provision of the 'enlargement or expansion ball I3, in the ingate, together with the risers and the sprue portion I5 of the gate is such that every casting formed is full, free from cracks and blowholes, and of uniform texture throughout.

-If desired, the members or studs 24 and 25 could be eliminated which would result in thicker sections between the wrist pin bosses and the piston heads. The provision of the enlargement or feeder I3 in the ingate assures supply 'of metal to such thicker sections during shrinkage.

In removing the cores from the finished castings, the core prints 52 are withdrawn first an then the cores.

The invention has been described herein more or less precisely as to details, yet it is to be understood that the invention is not tolbe limited thereby, as changes may be made `in the arrangement and proportion of parts and equivalents maybe substituted without departing from the spirit and scope of the invention.

cluding a pair of metallic mold parts hinged together for movement toward and away from each other, each of said parts having two horizontal complementa] cylindricalaxially spaced mold cavities opening through the ends of said parts and with the head ends in opposed relation and an ingate leading between the head ends of said cavities, formed therein; metallic cylindrical cores supported to Vlie horizontally within the mold cavities whensaid mold parts are together in casting relation; said. cores being axially movable so as to be withdrawn from the castings after the molding of the castings; said mold parts adapted to seat about said cores in sealing relation to cooperate therewith to form the remote ends of the mold cavities; said mold parts having openings to receive core prints for the wrist pin openings in the casting; said cores having'diametrically opposite substantially iiatl portions against which the inner ends of said core prints abut; said cores having radially extensible and retractible studs for forming lateral recesses in the castings; and -means entering said cores and operable while the mold parts are together for actuating said core studs into and out` of molding position.

2. An apparatus for group casting ofv pistons.

comprising a mold formed with a common runner arranged to supply metal to a plurality of piston casting cavities, said mold being formed cavities to supply molten metal to the larger voids of the' cavities to compensate for shrink-- age of the castings while cooling. i

3. An apparatus for group casting of pistons lcomprising a mold formed with a common run- 45 'ner arranged to supply metal to a plurality of piston casting cavities, said mold having formed in it a plurality pf piston -casting cavities arranged with the axes of the cavities horizontal and with the headiiflorming ends of said cavities in proximity to said common runner and .thev

` substantially horizontal arcas-1e skirt ends extending away from the common runner, cores supported in the skirt ends of said cavities to close said ends and form the interiors of the pistons, and said mold having a plurality of connections between said common runner and each of said cavities so arranged that the center lines of certain of said connections lie in horizontal planes which includes the horizontal axes of the cavities when the mold is in casting position.

4. In an apparatus for the group casting of pistons which comprises a mold formed with a common runner arranged to supply metal to a plurality of piston casting cavities, said runner being in vertical position when casting, said mold being formed with a plurality of piston casting cavities arranged with the axes of the cavities horizontal and with the head ends of said cavities in proximity to said common runner and with the skirt ends of the cavities extending away from the common runner, cores supported in the skirt ends of said cavities to form the interiors of the pistons and close said ends, and said mold being formed with connections between said common runner and said cavities, certain of said connections being so arranged that the centers thereof lie in vertical planes including the cavity axes when the mold is in casting position.

5. An apparatus for the group casting of pistons which includes aA mold formed with a common runner which extends vertically when in casting position and downwardly between' a plurality of piston cavities, said mold being formed with a plurality of piston cavities in it arranged with the head forming ends of said cavities towards the commonv runner and their axes at right angles to lthe longitudinal axis of the runner, means for supporting cores in the other ends o`f said cavities to formthe interiors of the pistons and close the ends of the cavities, and said mold having formed in it a plurality of connections between said runner and each of said cavities, certain of said connections.communicating with said cavities at substantiallyimid-height of said cavities when in casting positionl to supply metal to the larger voids in said cavities to compensate for shrinkage of the castings while cooling.

GEORGE H. BLE'I'INER. 

